3 files changed, 239 insertions, 223 deletions
diff --git a/gerber/excellon.py b/gerber/excellon.py
index 45a8e4b..072bc31 100755
--- a/gerber/excellon.py
+++ b/gerber/excellon.py
@@ -74,6 +74,11 @@ class ExcellonFile(CncFile):
             ctx.drill(pos[0], pos[1], tool.diameter)
         ctx.dump(filename)
 
+    def write(self, filename):
+        with open(filename, 'w') as f:
+            for statement in self.statements:
+                f.write(statement.to_excellon() + '\n')
+                
 
 class ExcellonParser(object):
     """ Excellon File Parser
@@ -155,9 +160,9 @@ class ExcellonParser(object):
 
         elif line[0] == 'T' and self.state != 'HEADER':
             stmt = ToolSelectionStmt.from_excellon(line)
-            self.active_tool self.tools[stmt.tool]
+            self.active_tool = self.tools[stmt.tool]
             #self.active_tool = self.tools[int(line.strip().split('T')[1])]
-            self.statements.append(statement)
+            self.statements.append(stmt)
             
         elif line[0] in ['X', 'Y']:
             stmt = CoordinateStmt.from_excellon(line, fmt, zs)
@@ -197,18 +202,8 @@ class ExcellonParser(object):
         return FileSettings(units=self.units, format=self.format,
                             zero_suppression=self.zero_suppression,
                             notation=self.notation)
-
-
-def pairwise(iterator):
-    """ Iterate over list taking two elements at a time.
-
-    e.g. [1, 2, 3, 4, 5, 6] ==> [(1, 2), (3, 4), (5, 6)]
-    """
-    itr = iter(iterator)
-    while True:
-        yield tuple([itr.next() for i in range(2)])
         
 
 if __name__ == '__main__':
-    p = parser()
-    p.parse('examples/ncdrill.txt')
+    p = ExcellonParser()
+    parsed = p.parse('examples/ncdrill.txt')
diff --git a/gerber/excellon_statements.py b/gerber/excellon_statements.py
index faadd20..09b72c1 100644
--- a/gerber/excellon_statements.py
+++ b/gerber/excellon_statements.py
@@ -15,10 +15,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from .utils import write_gerber_value
 
+from .utils import parse_gerber_value, write_gerber_value, decimal_string
+import re
 
-__all__ = ['ExcellonTool', 'ToolSelectionStatment', 'CoordinateStmt',
+__all__ = ['ExcellonTool', 'ToolSelectionStmt', 'CoordinateStmt',
            'CommentStmt', 'HeaderBeginStmt', 'HeaderEndStmt',
            'RewindStopStmt', 'EndOfProgramStmt', 'UnitStmt',
            'IncrementalModeStmt', 'VersionStmt', 'FormatStmt', 'LinkToolStmt',
@@ -138,20 +139,20 @@ class ExcellonTool(ExcellonStatement):
         fmt = self.settings['format']
         zs = self.settings['zero_suppression']
         stmt = 'T%d' % self.number
-        if self.retract_rate:
+        if self.retract_rate is not None:
             stmt += 'B%s' % write_gerber_value(self.retract_rate, fmt, zs)
-        if self.diameter:
-            stmt += 'C%s' % write_gerber_value(self.diameter, fmt, zs)
-        if self.feed_rate:
+        if self.feed_rate is not None:
             stmt += 'F%s' % write_gerber_value(self.feed_rate, fmt, zs)
-        if self.max_hit_count:
+        if self.max_hit_count is not None:
             stmt += 'H%s' % write_gerber_value(self.max_hit_count, fmt, zs)
-        if self.rpm:
+        if self.rpm is not None:
             if self.rpm < 100000.:
                 stmt += 'S%s' % write_gerber_value(self.rpm / 1000., fmt, zs)
             else:
                 stmt += 'S%g' % self.rpm / 1000.
-        if self.depth_offset:
+        if self.diameter is not None:
+            stmt += 'C%s' % decimal_string(self.diameter, 5, True)
+        if self.depth_offset is not None:
             stmt += 'Z%s' % write_gerber_value(self.depth_offset, fmt, zs)
         return stmt
 
@@ -163,7 +164,7 @@ class ExcellonTool(ExcellonStatement):
         return '<ExcellonTool %d: %0.3f%s dia.>' % (self.number, self.diameter, unit)
 
 
-class ToolSelectionStatment(ExcellonStatement):
+class ToolSelectionStmt(ExcellonStatement):
 
     @classmethod
     def from_excellon(cls, line):
@@ -189,6 +190,7 @@ class ToolSelectionStatment(ExcellonStatement):
 
 class CoordinateStmt(ExcellonStatement):
 
+    @classmethod
     def from_excellon(cls, line, format=(2, 5), zero_suppression='trailing'):
         x = None
         y = None
@@ -208,22 +210,23 @@ class CoordinateStmt(ExcellonStatement):
     def to_excellon(self):
         stmt = ''
         if self.x is not None:
-            stmt.append('X%s' % write_gerber_value(self.x))
+            stmt += 'X%s' % write_gerber_value(self.x)
         if self.y is not None:
-            stmt.append('Y%s' % write_gerber_value(self.y))
+            stmt += 'Y%s' % write_gerber_value(self.y)
         return stmt
 
 
 class CommentStmt(ExcellonStatement):
 
-    def from_excellon(self, line):
+    @classmethod
+    def from_excellon(cls, line):
         return cls(line.strip().lstrip(';'))
 
     def __init__(self, comment):
         self.comment = comment
 
     def to_excellon(self):
-        return ';%s' % comment
+        return ';%s' % self.comment
 
 
 class HeaderBeginStmt(ExcellonStatement):
@@ -265,7 +268,7 @@ class EndOfProgramStmt(ExcellonStatement):
             stmt += 'X%s' % write_gerber_value(self.x)
         if self.y is not None:
             stmt += 'Y%s' % write_gerber_value(self.y)
-
+        return stmt
 
 class UnitStmt(ExcellonStatement):
 
@@ -281,8 +284,9 @@ class UnitStmt(ExcellonStatement):
 
     def to_excellon(self):
         stmt = '%s,%s' % ('INCH' if self.units == 'inch' else 'METRIC',
-                          'LZ' if self.zero_suppression == 'trailing' else 'TZ')
-
+                          'LZ' if self.zero_suppression == 'trailing' 
+                          else 'TZ')
+        return stmt
 
 class IncrementalModeStmt(ExcellonStatement):
 
@@ -292,7 +296,7 @@ class IncrementalModeStmt(ExcellonStatement):
 
     def __init__(self, mode='off'):
         if mode.lower() not in ['on', 'off']:
-            raise ValueError('Mode may be "on" or "off")
+            raise ValueError('Mode may be "on" or "off"')
         self.mode = 'off'
 
     def to_excellon(self):
@@ -309,7 +313,7 @@ class VersionStmt(ExcellonStatement):
     def __init__(self, version=1):
         version = int(version)
         if version not in [1, 2]:
-            raise ValueError('Valid versions are  1 or 2'
+            raise ValueError('Valid versions are  1 or 2')
         self.version = version
 
     def to_excellon(self):
@@ -374,3 +378,15 @@ class UnknownStmt(ExcellonStatement):
 
     def to_excellon(self):
         return self.stmt
+
+        
+        
+        
+def pairwise(iterator):
+    """ Iterate over list taking two elements at a time.
+
+    e.g. [1, 2, 3, 4, 5, 6] ==> [(1, 2), (3, 4), (5, 6)]
+    """
+    itr = iter(iterator)
+    while True:
+        yield tuple([itr.next() for i in range(2)])
+\ No newline at end of file
diff --git a/gerber/utils.py b/gerber/utils.py
index 625a9e1..1721a7d 100644
--- a/gerber/utils.py
+++ b/gerber/utils.py
@@ -1,190 +1,195 @@
-#!/usr/bin/env python
-# -*- coding: utf-8 -*-
-"""
-gerber.utils
-============
-**Gerber and Excellon file handling utilities**
-
-This module provides utility functions for working with Gerber and Excellon
-files.
-"""
-
-# Author: Hamilton Kibbe <ham@hamiltonkib.be>
-# License:
-
-
-def parse_gerber_value(value, format=(2, 5), zero_suppression='trailing'):
-    """ Convert gerber/excellon formatted string to floating-point number
-
-    .. note::
-        Format and zero suppression are configurable. Note that the Excellon
-        and Gerber formats use opposite terminology with respect to leading
-        and trailing zeros. The Gerber format specifies which zeros are
-        suppressed, while the Excellon format specifies which zeros are
-        included. This function uses the Gerber-file convention, so an
-        Excellon file in LZ (leading zeros) mode would use
-        `zero_suppression='trailing'`
-
-
-    Parameters
-    ----------
-    value : string
-        A Gerber/Excellon-formatted string representing a numerical value.
-
-    format :  tuple (int,int)
-        Gerber/Excellon precision format expressed as a tuple containing:
-        (number of integer-part digits, number of decimal-part digits)
-
-    zero_suppression : string
-        Zero-suppression mode. May be 'leading' or 'trailing'
-
-    Returns
-    -------
-    value : float
-        The specified value as a floating-point number.
-
-    """
-    # Format precision
-    integer_digits, decimal_digits = format
-    MAX_DIGITS = integer_digits + decimal_digits
-
-    # Absolute maximum number of digits supported. This will handle up to
-    # 6:7 format, which is somewhat supported, even though the gerber spec
-    # only allows up to 6:6
-    if MAX_DIGITS > 13 or integer_digits > 6 or decimal_digits > 7:
-        raise ValueError('Parser only supports precision up to 6:7 format')
-
-    # Remove extraneous information
-    value = value.strip()
-    value = value.strip(' +')
-    negative = '-' in value
-    if negative:
-        value = value.strip(' -')
-
-    # Handle excellon edge case with explicit decimal. "That was easy!"
-    if '.' in value:
-        return float(value)
-
-    digits = [digit for digit in '0' * MAX_DIGITS]
-    offset = 0 if zero_suppression == 'trailing' else (MAX_DIGITS - len(value))
-    for i, digit in enumerate(value):
-        digits[i + offset] = digit
-
-    result = float(''.join(digits[:integer_digits] + ['.'] + digits[integer_digits:]))
-    return -1.0 * result if negative else result
-
-
-def write_gerber_value(value, format=(2, 5), zero_suppression='trailing'):
-    """ Convert a floating point number to a Gerber/Excellon-formatted string.
-
-    .. note::
-        Format and zero suppression are configurable. Note that the Excellon
-        and Gerber formats use opposite terminology with respect to leading
-        and trailing zeros. The Gerber format specifies which zeros are
-        suppressed, while the Excellon format specifies which zeros are
-        included. This function uses the Gerber-file convention, so an
-        Excellon file in LZ (leading zeros) mode would use
-        `zero_suppression='trailing'`
-
-    Parameters
-    ----------
-    value : float
-        A floating point value.
-
-    format :  tuple (n=2)
-        Gerber/Excellon precision format expressed as a tuple containing:
-        (number of integer-part digits, number of decimal-part digits)
-
-    zero_suppression : string
-        Zero-suppression mode. May be 'leading' or 'trailing'
-
-    Returns
-    -------
-    value : string
-        The specified value as a Gerber/Excellon-formatted string.
-    """
-    # Format precision
-    integer_digits, decimal_digits = format
-    MAX_DIGITS = integer_digits + decimal_digits
-
-    if MAX_DIGITS > 13 or integer_digits > 6 or decimal_digits > 7:
-        raise ValueError('Parser only supports precision up to 6:7 format')
-
-    # negative sign affects padding, so deal with it at the end...
-    negative = value < 0.0
-    if negative:
-        value = -1.0 * value
-
-    # Format string for padding out in both directions
-    fmtstring = '%%0%d.0%df' % (MAX_DIGITS + 1, decimal_digits)
-
-    digits = [val for val in fmtstring % value if val != '.']
-
-    # Suppression...
-    if zero_suppression == 'trailing':
-        while digits[-1] == '0':
-            digits.pop()
-    else:
-        while digits[0] == '0':
-            digits.pop(0)
-
-    return ''.join(digits) if not negative else ''.join(['-'] + digits)
-
-
-def decimal_string(value, precision=6):
-    """ Convert float to string with limited precision
-
-    Parameters
-    ----------
-    value : float
-        A floating point value.
-
-    precision :
-        Maximum number of decimal places to print
-
-    Returns
-    -------
-    value : string
-        The specified value as a  string.
-
-    """
-    floatstr = '%0.20g' % value
-    integer = None
-    decimal = None
-    if '.' in floatstr:
-        integer, decimal = floatstr.split('.')
-    elif ',' in floatstr:
-        integer, decimal = floatstr.split(',')
-    if len(decimal) > precision:
-        decimal = decimal[:precision]
-    if integer or decimal:
-        return ''.join([integer, '.', decimal])
-    else:
-        return int(floatstr)
-
-
-def detect_file_format(filename):
-    """ Determine format of a file
-
-    Parameters
-    ----------
-    filename : string
-        Filename of the file to read.
-
-    Returns
-    -------
-    format : string
-        File format. either 'excellon' or 'rs274x'
-    """
-
-    # Read the first 20 lines
-    with open(filename, 'r') as f:
-        lines = [next(f) for x in xrange(20)]
-
-    # Look for
-    for line in lines:
-        if 'M48' in line:
-            return 'excellon'
-        elif '%FS' in line:
-            return'rs274x'
-    return 'unknown'
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+"""
+gerber.utils
+============
+**Gerber and Excellon file handling utilities**
+
+This module provides utility functions for working with Gerber and Excellon
+files.
+"""
+
+# Author: Hamilton Kibbe <ham@hamiltonkib.be>
+# License:
+
+
+def parse_gerber_value(value, format=(2, 5), zero_suppression='trailing'):
+    """ Convert gerber/excellon formatted string to floating-point number
+
+    .. note::
+        Format and zero suppression are configurable. Note that the Excellon
+        and Gerber formats use opposite terminology with respect to leading
+        and trailing zeros. The Gerber format specifies which zeros are
+        suppressed, while the Excellon format specifies which zeros are
+        included. This function uses the Gerber-file convention, so an
+        Excellon file in LZ (leading zeros) mode would use
+        `zero_suppression='trailing'`
+
+
+    Parameters
+    ----------
+    value : string
+        A Gerber/Excellon-formatted string representing a numerical value.
+
+    format :  tuple (int,int)
+        Gerber/Excellon precision format expressed as a tuple containing:
+        (number of integer-part digits, number of decimal-part digits)
+
+    zero_suppression : string
+        Zero-suppression mode. May be 'leading' or 'trailing'
+
+    Returns
+    -------
+    value : float
+        The specified value as a floating-point number.
+
+    """
+    # Format precision
+    integer_digits, decimal_digits = format
+    MAX_DIGITS = integer_digits + decimal_digits
+
+    # Absolute maximum number of digits supported. This will handle up to
+    # 6:7 format, which is somewhat supported, even though the gerber spec
+    # only allows up to 6:6
+    if MAX_DIGITS > 13 or integer_digits > 6 or decimal_digits > 7:
+        raise ValueError('Parser only supports precision up to 6:7 format')
+
+    # Remove extraneous information
+    value = value.strip()
+    value = value.strip(' +')
+    negative = '-' in value
+    if negative:
+        value = value.strip(' -')
+
+    # Handle excellon edge case with explicit decimal. "That was easy!"
+    if '.' in value:
+        return float(value)
+
+    digits = [digit for digit in '0' * MAX_DIGITS]
+    offset = 0 if zero_suppression == 'trailing' else (MAX_DIGITS - len(value))
+    for i, digit in enumerate(value):
+        digits[i + offset] = digit
+
+    result = float(''.join(digits[:integer_digits] + ['.'] + digits[integer_digits:]))
+    return -1.0 * result if negative else result
+
+
+def write_gerber_value(value, format=(2, 5), zero_suppression='trailing'):
+    """ Convert a floating point number to a Gerber/Excellon-formatted string.
+
+    .. note::
+        Format and zero suppression are configurable. Note that the Excellon
+        and Gerber formats use opposite terminology with respect to leading
+        and trailing zeros. The Gerber format specifies which zeros are
+        suppressed, while the Excellon format specifies which zeros are
+        included. This function uses the Gerber-file convention, so an
+        Excellon file in LZ (leading zeros) mode would use
+        `zero_suppression='trailing'`
+
+    Parameters
+    ----------
+    value : float
+        A floating point value.
+
+    format :  tuple (n=2)
+        Gerber/Excellon precision format expressed as a tuple containing:
+        (number of integer-part digits, number of decimal-part digits)
+
+    zero_suppression : string
+        Zero-suppression mode. May be 'leading' or 'trailing'
+
+    Returns
+    -------
+    value : string
+        The specified value as a Gerber/Excellon-formatted string.
+    """
+    # Format precision
+    integer_digits, decimal_digits = format
+    MAX_DIGITS = integer_digits + decimal_digits
+
+    if MAX_DIGITS > 13 or integer_digits > 6 or decimal_digits > 7:
+        raise ValueError('Parser only supports precision up to 6:7 format')
+
+    # Edge case...
+    if value == 0:
+        return '00'
+        
+    # negative sign affects padding, so deal with it at the end...
+    negative = value < 0.0
+    if negative:
+        value = -1.0 * value
+
+    # Format string for padding out in both directions
+    fmtstring = '%%0%d.0%df' % (MAX_DIGITS + 1, decimal_digits)
+    digits = [val for val in fmtstring % value if val != '.']
+
+    # Suppression...
+    if zero_suppression == 'trailing':
+        while digits[-1] == '0':
+            digits.pop()
+    else:
+        while digits[0] == '0':
+            digits.pop(0)
+
+    return ''.join(digits) if not negative else ''.join(['-'] + digits)
+
+
+def decimal_string(value, precision=6, padding=False):
+    """ Convert float to string with limited precision
+
+    Parameters
+    ----------
+    value : float
+        A floating point value.
+
+    precision :
+        Maximum number of decimal places to print
+
+    Returns
+    -------
+    value : string
+        The specified value as a  string.
+
+    """
+    floatstr = '%0.10g' % value
+    integer = None
+    decimal = None
+    if '.' in floatstr:
+        integer, decimal = floatstr.split('.')
+    elif ',' in floatstr:
+        integer, decimal = floatstr.split(',')
+    if len(decimal) > precision:
+        decimal = decimal[:precision]
+    elif padding:
+        decimal = decimal + (precision - len(decimal)) * '0'
+    if integer or decimal:
+        return ''.join([integer, '.', decimal])
+    else:
+        return int(floatstr)
+
+
+def detect_file_format(filename):
+    """ Determine format of a file
+
+    Parameters
+    ----------
+    filename : string
+        Filename of the file to read.
+
+    Returns
+    -------
+    format : string
+        File format. either 'excellon' or 'rs274x'
+    """
+
+    # Read the first 20 lines
+    with open(filename, 'r') as f:
+        lines = [next(f) for x in xrange(20)]
+
+    # Look for
+    for line in lines:
+        if 'M48' in line:
+            return 'excellon'
+        elif '%FS' in line:
+            return'rs274x'
+    return 'unknown'